BoilerFaultCodesThe 6 most common faults
Your boiler has detected that there is not enough water in the system to operate safely, causing it to shut down temporarily.
Why it happens: This fault occurs when the internal sensors detect that the water pressure has dropped below the minimum level required to circulate heat safely. The most common reason is a small leak somewhere in the central heating pipework or radiators, though it can also happen if you have recently bled your radiators without topping the system back up.
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the one or two taps/valves on the filling loop until you hear water entering the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps fully.
Your boiler has detected that water isn't moving through the system properly, which is causing it to overheat and shut down for safety.
Why it happens: This fault occurs when the boiler's internal sensors detect that the water temperature is rising too quickly because it isn't being moved away from the burner. The most common reason is a seized or failing pump, though it can also be caused by an airlock or a blockage in the system preventing the water from flowing. For your safety, the boiler shuts down immediately to prevent the heat exchanger from reaching dangerous temperatures.
Check that your system pressure is between 1 and 1.5 bar on the pressure gaugeEnsure all radiator valves and isolation valves under the boiler are fully openBleed your radiators to remove any trapped air pockets
Your boiler has tried to ignite but failed to stay alight, which is often caused by a lack of gas supply or a blocked condensation pipe.
Why it happens: This fault occurs when the boiler's control system attempts to light the burner but cannot detect a stable flame. The most common reasons are a temporary interruption in the gas supply, an ignition electrode that is too dirty to spark, or a blockage in the pipe that carries away waste water.
Check that your gas supply is turned on and you have credit on your meter.During freezing weather, check if your external white plastic condensate pipe is frozen and thaw it with warm water.Press the Reset button for five seconds.
Your boiler started to heat up but the flame went out unexpectedly while it was running.
Why it happens: This fault occurs when the boiler successfully lights, but the internal sensors lose track of the flame while it is running, causing the system to shut down for safety. The most common reasons are a worn-out sensing probe that can no longer 'see' the fire, or an unstable gas supply that prevents the flame from staying consistent.
Check that your gas pre-pay meter has creditEnsure other gas appliances in your home are working to confirm gas supplyPress the 'Reset' button for five seconds
Your boiler has detected that it is getting too hot or that water isn't moving through the system correctly, causing it to shut down for safety.
Why it happens: This fault occurs when the internal sensors detect that the water temperature inside the boiler has exceeded safe limits, triggered by a lack of circulation. The most common reasons are a failed pump that isn't pushing water around the system, or a blockage caused by a build-up of debris or air. In some cases, the sensors themselves may have become faulty and are providing an incorrect reading to the control board.
Check that your radiator valves are openEnsure your system water pressure is between 1 and 1.5 bar on the gaugeReset the boiler by turning the selector switch to 'R' for five seconds
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety sensor to cut the power. The most common reasons are a pump failure preventing water from circulating or a blockage caused by sludge and debris inside the central heating pipework. In some cases, it can be caused by air trapped in the system or a faulty sensor providing an incorrect reading.
Check that your radiator valves are open and not turned to zero.Ensure your system water pressure is between 1 and 1.5 bar on the gauge.Turn the selector switch to the reset position for five seconds and then back to 'onn'.
on the Baxi EcoBlue Plus Combi
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Baxi shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue